An example of a conventional one-way clutch having no retainers, as shown in FIGS. 1 and 2, uses a plurality of sprags S inserted, one in contact with another, between concentric outer and inner rings 1 and 2, respectively, one of which rotatably drives the other. An annular garter spring 5 is fitted in a groove 4 provided on each side of the sprag. An annular side plate 6 is disposed on each side of the sprag.
An example of a conventional one-way clutch having a retainer, as shown in FIGS. 3 and 4, uses a plurality of sprags S' inserted at intervals between the outer ring 1 and the inner ring 2. A retainer 8, made of steel sheet punched with a sprag inserting hole 7, is used to keep the sprags spaced at given intervals.
In the former type, shown in FIGS. 1 and 2, each sprag contacts adjacent sprags so that the axis of rotation thereof coincides with those of the outer and inner rings. Thus, the adjacent sprags interfere with each other to prevent smooth motion, with the points of contact moving in opposite directions as indicated by the arrows. Governed by the circumferential length of the outer and inner rings, the number of sprags cannot be decreased according to the required torque. Provision of the groove 4 to insert the garter spring 5 on each side of the sprag reduces the area of contact between the side of the sprag and the annular side plate 6. Consequently, if the sprag gives a localized axial push to the annular side plate 6, localized abrasive wear is likely to occur. Especially if the annular side plate 6 warps outward (in the side not contacting a stopper ring 21), the localized abrasive wear increases, greatly preventing the smooth motion of the sprags.
In the clutch shown in FIGS. 3 and 4, blanking the retainer 8 from thin steel sheet develops burrs which prevent the sprag from moving smoothly along and around the axis, and causes the sprag inserting hole 7 to easily wear.
Moreover, in the conventional one-way clutch either with or without a retainer, it is necessary to provide an additional bearing 33 between the outer and inner rings as shown in FIG. 5 for the purpose of centering said rings and bearing the radial load during idle rotation.
This invention eliminates the aforementioned short-comings of conventional one-way clutches.
Our copending application Ser. No. 198 420, filed Oct. 20, 1980, now Pat. No. 4,360,093 discloses therein an improved one-way clutch of the sprag type which eliminates the aforementioned shortcomings of conventional clutches and hence represents a substantial improvement thereover. However, while the improved clutch of the aforesaid application has proven highly desirable, nevertheless further ongoing developments and modifications have been made therein so as to still further improve this one-way sprag clutch with respect to its structure, size and/or performance. More specifically, the improved clutch of this invention incorporates therein an improved side plate member which extends radially between and slidably engages the inner and outer rings, and is axially confined between the sides of the sprags and the circumferentially extending parts of the retainer, whereby the improved side plates members effectively function as a bearing to maintain proper concentricity between the inner and outer rings and even permit idle rotation therebetween, while at the same time effectively resisting side thrust from the sprags so as to insure more uniform torque distribution among the plurality of sprags.
Accordingly, in the improved one-way clutch of the present invention, a plurality of sprags disposed in an annular array are positioned within an annular space between concentric inner and outer rings. Each sprag has a groove formed therein substantially midway between the ends thereof, which groove extends radially relative to the inner and outer rings and is effectively defined by a plane which is substantially perpendicular to the rotational axis of the clutch. A garter spring is fitted within the grooves defined by the plurality of sprags. An annular retainer is disposed within the annular space for holding and positionally confining the sprags. The annular retainer has axially extending parts which extend axially between adjacent sprags for positionally holding the sprags between the inner and outer rings, and which axially extending parts are joined together by circumferentially extending parts. These axially and circumferentially extending parts preferably define adjacent U-shaped portions which alternately open in axially opposite directions. A platelike side member is disposed adjacent each end surface of the plurality of sprags, which side member comprises an annular ring which has inner and outer walls which effectively slidably engage the respective inner and outer rings, which inner and outer walls are joined by a radial side wall which closely slidably confines the adjacent end walls of the sprags. This side member also has a plurality of circumferentially spaced recesses formed radially therein, which recesses accommodate the axially extending parts of the retainer, and the radial side wall of the side member has radially projecting portions which are positionable between the ends of the sprags and the circumferentially extending parts of the retainer.
Other objects and purposes of the invention will be apparent from the following detailed description.